Phylogeography of Coastal Fishes of Japan

Fish fauna and environmental factors in river estuaries of small and medium‐sized rivers on islands significantly influenced by warm currents

“…Tanegashima Island, the subject of this study, is located in the Nansei Islands and is known to be a biogeographic boundary for terrestrial animals and shallow‐water fishes as a result of the existence of submarine valleys with water depths exceeding 1000 m (Kimura, 1996), called the Tokara Gap and the Kerama Gap (Komaki, 2021; Sakai et al, 2005). Recently, however, a comprehensive survey of the ichthyofauna of the Kuroshio coastal area has revealed a boundary between them, called the Osumi Line, between Yakushima Island and Tanegashima, Iwojima, and Takeshima Islands in the Osumi Islands have been shown to be the boundary of the fish fauna of southern Japan (Matsui, 2022; Motomura & Matsunuma, 2022). However, these studies were mainly conducted in shallow‐water areas, and the relationship between the fish fauna and environmental factors in the river estuaries of the islands of the Nansei Islands has not been clarified.…”

“…However, there is less information available on small and medium-sized rivers in peninsulas and islands. On islands and peninsulas where currents are complex and the topography is relatively complex, the biota are fragmented, with adjacent rivers having different biota (Itsukushima & Kano, 2021, 2022, therefore examining the biota of small and medium-sized rivers on islands and peninsulas, and their relationship with environmental factors is vital information for environmental conservation and ecological restoration. Tanegashima Island, the subject of this study, is located in the Nansei Islands and is known to be a biogeographic boundary for terrestrial animals and shallow-water fishes as a result of the existence of submarine valleys with water depths exceeding 1000 m (Kimura, 1996), called the Tokara Gap and the Kerama Gap (Komaki, 2021;Sakai et al, 2005).…”

Contrasting population genetic structure of three semi‐terrestrial brachyuran crabs on the coast of the Japanese archipelago

“…Indeed, in addition to anthropogenic activities, various factors, such as the dispersal ability of the planktonic larval stages (DeWoody & Avise, 2000 ; Palumbi, 1992 ) and ocean currents as invisible physical barriers (Gilg & Hilbish, 2003 ; Palumbi, 1992 ), are known to affect the population genetic structure of coastal invertebrates. In the Japanese archipelago, several ocean currents, including Oyashio, Kuroshio and Tsushima currents, are known to genetically differentiate the local populations of coastal organisms, such as gobies (Matsui, 2022 ), snails (Kojima et al., 2004 ; Nakano et al., 2010 ; Yamakawa & Imai, 2014 ) and the seaweeds (Hu et al., 2016 ; Zhong et al., 2020 ). These organisms have phylogeographic patterns composed of “Pacific Ocean lineage” and “Sea of Japan lineage,” which correspond to the paths of the two currents, the Kuroshio Current and the Tsushima Current, respectively (Matsui, 2022 ).…”

“…In the Japanese archipelago, several ocean currents, including Oyashio, Kuroshio and Tsushima currents, are known to genetically differentiate the local populations of coastal organisms, such as gobies (Matsui, 2022 ), snails (Kojima et al., 2004 ; Nakano et al., 2010 ; Yamakawa & Imai, 2014 ) and the seaweeds (Hu et al., 2016 ; Zhong et al., 2020 ). These organisms have phylogeographic patterns composed of “Pacific Ocean lineage” and “Sea of Japan lineage,” which correspond to the paths of the two currents, the Kuroshio Current and the Tsushima Current, respectively (Matsui, 2022 ). Although several studies have examined the genetic population structure of brachyuran crabs, such as the varunid crab Ptychognathus ishii (Kawane & Wada, 2015 ), the sesarmid crab Clistocoeloma sinense (Yuhara et al., 2014 ), the camptandriid crabs Deiratonotus cristatus (Kawamoto et al., 2012 ) and Deiratonotus kaorie (Kawane et al., 2012 ), and the ocypodid crabs Austruca lactea (Tokuyama et al., 2020 ) and Tubuca arcuata (Aoki et al., 2008 ), the factors affecting their genetic structure are not well understood, since the distribution ranges of these crabs are geographically restricted to the limited area of the Japanese coast.…”